kernel.git/drivers/pci/iov.c, branch linux-5.4.y

PCI/IOV: Add PCI rescan-remove locking when enabling/disabling SR-IOV

2025-10-29T12:59:54Z

commit 05703271c3cdcc0f2a8cf6ebdc45892b8ca83520 upstream. Before disabling SR-IOV via config space accesses to the parent PF, sriov_disable() first removes the PCI devices representing the VFs. Since commit 9d16947b7583 ("PCI: Add global pci_lock_rescan_remove()") such removal operations are serialized against concurrent remove and rescan using the pci_rescan_remove_lock. No such locking was ever added in sriov_disable() however. In particular when commit 18f9e9d150fc ("PCI/IOV: Factor out sriov_add_vfs()") factored out the PCI device removal into sriov_del_vfs() there was still no locking around the pci_iov_remove_virtfn() calls. On s390 the lack of serialization in sriov_disable() may cause double remove and list corruption with the below (amended) trace being observed: PSW: 0704c00180000000 0000000c914e4b38 (klist_put+56) GPRS: 000003800313fb48 0000000000000000 0000000100000001 0000000000000001 00000000f9b520a8 0000000000000000 0000000000002fbd 00000000f4cc9480 0000000000000001 0000000000000000 0000000000000000 0000000180692828 00000000818e8000 000003800313fe2c 000003800313fb20 000003800313fad8 #0 [3800313fb20] device_del at c9158ad5c #1 [3800313fb88] pci_remove_bus_device at c915105ba #2 [3800313fbd0] pci_iov_remove_virtfn at c9152f198 #3 [3800313fc28] zpci_iov_remove_virtfn at c90fb67c0 #4 [3800313fc60] zpci_bus_remove_device at c90fb6104 #5 [3800313fca0] __zpci_event_availability at c90fb3dca #6 [3800313fd08] chsc_process_sei_nt0 at c918fe4a2 #7 [3800313fd60] crw_collect_info at c91905822 #8 [3800313fe10] kthread at c90feb390 #9 [3800313fe68] __ret_from_fork at c90f6aa64 #10 [3800313fe98] ret_from_fork at c9194f3f2. This is because in addition to sriov_disable() removing the VFs, the platform also generates hot-unplug events for the VFs. This being the reverse operation to the hotplug events generated by sriov_enable() and handled via pdev->no_vf_scan. And while the event processing takes pci_rescan_remove_lock and checks whether the struct pci_dev still exists, the lack of synchronization makes this checking racy. Other races may also be possible of course though given that this lack of locking persisted so long observable races seem very rare. Even on s390 the list corruption was only observed with certain devices since the platform events are only triggered by config accesses after the removal, so as long as the removal finished synchronously they would not race. Either way the locking is missing so fix this by adding it to the sriov_del_vfs() helper. Just like PCI rescan-remove, locking is also missing in sriov_add_vfs() including for the error case where pci_stop_and_remove_bus_device() is called without the PCI rescan-remove lock being held. Even in the non-error case, adding new PCI devices and buses should be serialized via the PCI rescan-remove lock. Add the necessary locking. Fixes: 18f9e9d150fc ("PCI/IOV: Factor out sriov_add_vfs()") Signed-off-by: Niklas Schnelle Signed-off-by: Bjorn Helgaas Reviewed-by: Benjamin Block Reviewed-by: Farhan Ali Reviewed-by: Julian Ruess Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20250826-pci_fix_sriov_disable-v1-1-2d0bc938f2a3@linux.ibm.com Signed-off-by: Greg Kroah-Hartman

PCI/IOV: Mark VFs as not implementing PCI_COMMAND_MEMORY

2020-10-29T08:57:54Z

[ Upstream commit 12856e7acde4702b7c3238c15fcba86ff6aa507f ] For VFs, the Memory Space Enable bit in the Command Register is hard-wired to 0. Add a new bit to signify devices where the Command Register Memory Space Enable bit does not control the device's response to MMIO accesses. Fixes: abafbc551fdd ("vfio-pci: Invalidate mmaps and block MMIO access on disabled memory") Signed-off-by: Matthew Rosato Acked-by: Bjorn Helgaas Signed-off-by: Alex Williamson Signed-off-by: Sasha Levin

PCI/IOV: Serialize sysfs sriov_numvfs reads vs writes

2020-10-01T11:17:12Z

[ Upstream commit 35ff867b76576e32f34c698ccd11343f7d616204 ] When sriov_numvfs is being updated, we call the driver->sriov_configure() function, which may enable VFs and call probe functions, which may make new devices visible. This all happens before before sriov_numvfs_store() updates sriov->num_VFs, so previously, concurrent sysfs reads of sriov_numvfs returned stale values. Serialize the sysfs read vs the write so the read returns the correct num_VFs value. [bhelgaas: hold device_lock instead of checking mutex_is_locked()] Link: https://bugzilla.kernel.org/show_bug.cgi?id=202991 Link: https://lore.kernel.org/r/20190911072736.32091-1-pierre.cregut@orange.com Signed-off-by: Pierre Crégut Signed-off-by: Bjorn Helgaas Signed-off-by: Sasha Levin

PCI/IOV: Fix memory leak in pci_iov_add_virtfn()

2020-02-14T21:34:08Z

commit 8c386cc817878588195dde38e919aa6ba9409d58 upstream. In the implementation of pci_iov_add_virtfn() the allocated virtfn is leaked if pci_setup_device() fails. The error handling is not calling pci_stop_and_remove_bus_device(). Change the goto label to failed2. Fixes: 156c55325d30 ("PCI: Check for pci_setup_device() failure in pci_iov_add_virtfn()") Link: https://lore.kernel.org/r/20191125195255.23740-1-navid.emamdoost@gmail.com Signed-off-by: Navid Emamdoost Signed-off-by: Bjorn Helgaas Signed-off-by: Greg Kroah-Hartman

Merge branch 'pci/resource'

2019-09-23T21:10:15Z

- Convert pci_resource_to_user() to a weak function to remove HAVE_ARCH_PCI_RESOURCE_TO_USER #defines (Denis Efremov) - Use PCI_SRIOV_NUM_BARS for idiomatic loop structure (Denis Efremov) - Fix Resizable BAR size suspend/restore for 1MB BARs (Sumit Saxena) - Correct "pci=resource_alignment" example in documentation (Alexey Kardashevskiy) * pci/resource: PCI: Correct pci=resource_alignment parameter example PCI: Restore Resizable BAR size bits correctly for 1MB BARs PCI: Use PCI_SRIOV_NUM_BARS in loops instead of PCI_IOV_RESOURCE_END PCI: Convert pci_resource_to_user() to a weak function # Conflicts: # drivers/pci/pci.c

PCI/IOV: Remove group write permission from sriov_numvfs, sriov_drivers_autoprobe

2019-09-05T18:26:23Z

Previously the sriov_numvfs and sriov_drivers_autoprobe sysfs files had 0664 permissions, which allowed group write. libvirt runs as root when dealing with PCI, and it chowns files needed by qemu, so group write permission should not be needed. Change these permissions from 0664 to 0644, which is what DEVICE_ATTR_RW() does by default. [bhelgaas: commit log] Link: https://lore.kernel.org/r/20190905063226.43269-1-skunberg.kelsey@gmail.com Link: https://lore.kernel.org/r/850cf536-0b72-d78c-efaf-855dcb391087@redhat.com Signed-off-by: Kelsey Skunberg Signed-off-by: Bjorn Helgaas Reviewed-by: Greg Kroah-Hartman Acked-by: Donald Dutile

PCI/IOV: Move sysfs SR-IOV functions to iov.c

2019-08-20T19:05:05Z

The sysfs SR-IOV functions are only needed when the kernel is built with SR-IOV support. Rather than put them in pci-sysfs.c under #ifdef CONFIG_PCI_IOV, move them to iov.c, which is only compiled when CONFIG_PCI_IOV=y. Link: https://lore.kernel.org/r/20190813204513.4790-4-skunberg.kelsey@gmail.com Signed-off-by: Kelsey Skunberg Signed-off-by: Bjorn Helgaas Reviewed-by: Greg Kroah-Hartman Reviewed-by: Donald Dutile Reviewed-by: Kuppuswamy Sathyanarayanan

PCI: Use PCI_SRIOV_NUM_BARS in loops instead of PCI_IOV_RESOURCE_END

2019-08-08T20:12:12Z

Writing loop conditions as "i < NUM" is a common C idiom; using "i <= END" is unusual and thus prone to errors. Change loops to use the former. Link: https://lore.kernel.org/r/20190806140715.19847-1-efremov@linux.com Signed-off-by: Denis Efremov Signed-off-by: Bjorn Helgaas Reviewed-by: Kuppuswamy Sathyanarayanan

Revert "PCI/IOV: Use VF0 cached config space size for other VFs"

2019-07-03T13:58:19Z

Revert 975bb8b4dc93 ("PCI/IOV: Use VF0 cached config space size for other VFs"), which attempted to cache the config space size from the first VF to re-use for subsequent VFs. The cached value was determined prior to discovering the PCIe capability on the VF, which resulted in the first VF reporting the correct config space size (4K), as it has a special case through pci_cfg_space_size(), while all the other VFs only reported 256 bytes. As this was only a performance optimization, we're better off without it. Fixes: 975bb8b4dc93 ("PCI/IOV: Use VF0 cached config space size for other VFs") Link: https://lore.kernel.org/r/156046663197.29869.3633634445109057665.stgit@gimli.home Signed-off-by: Alex Williamson Signed-off-by: Bjorn Helgaas Cc: KarimAllah Ahmed Cc: Kuppuswamy Sathyanarayanan Cc: Hao Zheng

PCI/IOV: Add flag so platforms can skip VF scanning

2019-01-02T01:04:37Z

Provide a flag to skip scanning for new VFs after SR-IOV enablement. This can be set by implementations for which the VFs are already reported by other means. Signed-off-by: Sebastian Ott Signed-off-by: Bjorn Helgaas Reviewed-by: Christoph Hellwig